The present invention relates to an image correcting apparatus; and, more particularly, to an apparatus for gamma correcting image data, which is capable of reducing a chip size.
Generally, in a gamma correction of a red (R) image data DRED, a green (G) image data DGREEN, and a blue (B) image data DBLUE, each gamma corrected data is obtained by using exponential functions. However, it is difficult to correctly implement the exponential function by using hardware elements, and, if possible, a lot of hardware elements are required.
FIG. 1 is a block diagram showing a conventional gamma correction apparatus using lookup tables. The lookup tables stores gamma corrected data that are previously calculated. The lookup tables are stored in a storage unit such as ROM (read only memory) and RAM (random access memory).
As shown in FIG. 1, the conventional gamma correction apparatus includes a latch portion 100 for latching image data, a lookup table portion 108 for storing gamma corrected data with respect to the image data, and a gamma latch portion 116 for latching the gamma corrected data outputted from the lookup table portion 108.
The latch portion 100 includes an R latch 102 for latching a red image data DRED, a G latch 104 for latching a green color image data DGREEN, and a B latch 106 for latching a blue color image data DBLUE.
The lookup table portion 108 includes a first lookup table 110 for storing a gamma corrected red image data, a second lookup table 112 for storing a gamma corrected green image data, and a third lookup table 114 for storing a gamma corrected blue image data.
The gamma latch portion 116 includes an R gamma latch 118, a G gamma latch 120, and a B gamma latch 122. The R gamma latch 118 latches the gamma corrected red image data that are outputted from the first lookup table 110. The G gamma latch 120 latches the gamma corrected green image data that are outputted from the second lookup table 112. The B gamma latch 122 latches the gamma corrected blue image data that are outputted from the third lookup table 122.
In such a conventional gamma correction apparatus, R, G, and G linear image data are latched to corresponding latch circuits 102, 104 and 106, respectively. Then, gamma corrected data corresponding to the linear image data is outputted from respective lookup tables. The gamma corrected data read out are latched and outputted to a next image processing circuit. Each gamma corrected data from the gamma latch portion 116 is transferred to a next image processing unit.
In such a conventional gamma correction apparatus, one image data is latched in a corresponding latch and a gamma corrected image data of corresponding image data is outputted to the gamma latch. Then, the gamma corrected image data stored in the gamma latch is outputted to a next image process unit.
However, since the conventional gamma correction apparatus employs individual lookup tables for storing the gamma corrected image data, the hardware elements for implementing the lookup tables are required, thereby increasing a chip size.
It is, therefore, an object of the present invention to provide an apparatus for gamma correcting image data in an image sensor, capable of reducing a chip size.
In accordance with an aspect of the present invention, there is provided an apparatus for gamma correcting image data including a first image data, a second image data and a third image data, the apparatus comprising: a first clock generating means for generating a first clock; a second clock generating means for generating a second clock, wherein the second clock has a frequency a predetermined times as fast as the first clock; an image data input means for storing the image data in response to a first clock; a first selecting means for selectively outputting the image data in response to a second clock; a second selecting means for selectively outputting a starting point value of corresponding image data in response to the second clock; a third selecting means for selectively outputting a gamma slope value of corresponding image data in response to the second clock; a piecewise gamma correction means for receiving output values from the first, the second and the third selecting means to generate gamma corrected image data; and an output means for storing the gamma corrected image data a predetermined time and outputting the gamma corrected image data in response to the second clock.